1. Field of the Invention
This invention relates to valve systems of the type adapted to allow the introduction of a surgical instrument into a patient's body, In particular, the invention is applicable to a cannula assembly wherein a cannula extends from the valve assembly and is intended for insertion into a patient's body to accommodate an instrument inserted through the cannula and valve.
2. Background of the Prior Art
In laparoscopic procedures surgery is performed in the interior of the abdomen through a small incision; in endoscopic procedures surgery is performed in any hollow viscus of the body through narrow tubes or cannula inserted through a small entrance incision in the skin. Laparoscopic and endoscopic procedures generally require that any instrumentation inserted into the body be sealed, i.e. provisions must be made to ensure that gases do not enter or exit the body through the incision as, for example, in surgical procedures in which the surgical region is insufflated. Moreover, laparoscopic and endoscopic procedures often require the surgeon to act on organs, tissues, and vessels far removed from the incision, thereby requiring that any instruments used in such procedures be relatively long and narrow.
For such procedures, the introduction of a tube into certain anatomical cavities such as the abdominal cavity is usually accomplished by use of a trocar assembly comprised of a cannula assembly and an obturator. The cannula assembly includes a cannula tube attached to a valve assembly which is adapted to maintain a seal across the opening of the cannula assembly. Since the cannula tube is in direct communication with the internal portion of the valve assembly, insertion of the cannula tube into an opening in the patient's body so as to reach the inner abdominal cavity must maintain a relatively gas-tight interface between the abdominal cavity and the outside atmosphere.
Since surgical procedures in the abdominal cavity of the body require insufflating gases to raise the cavity wall away from vital organs, the procedure is usually initiated by use of a Verres needle through which a gas such as CO.sub.2 is introduced into the body cavity. Thereafter, the pointed obturator of the trocar assembly is inserted into the cannula assembly and used to puncture the abdominal cavity wall. The gas provides a slight pressure which raises the inner wall surface away from the vital organs thereby avoiding unnecessary contact with the organs by the instruments inserted into the cannula. Following removal of the obturator, laparoscopic or endoscopic surgical instruments may then be inserted through the cannula assembly to perform surgery within the abdominal cavity.
In view of the need to prevent leakage of the insufflation gas from the cavity, the cannula is typically provided with a valve assembly which permits introduction of surgical instruments to provide selective communication between the inner atmosphere of the cavity with the outside atmosphere. In this regard, there have been a number of attempts in the prior art to provide such a seal as part of the cannula assembly.
One form of cannula assembly includes a flapper valve which is pivotally mounted within the cannula assembly and is automatically opened by the obturator or other object when it is inserted into the proximal end of the cannula. Conventional flapper valves may also be manually opened by pivoting a lever on the exterior of the cannula housing. See, e.g., U.S. Pat. No. 4,943,280 to Lander. Trumpet valves are also known.
U.S. Pat. No. 4,655,752 to Honkanen et al. discloses a cannula including a housing and first and second seal members. The first seal member is conically tapered towards the bottom of the housing and has a circular opening in its center, while the second seal member is cup-shaped and also possesses a conically tapered bottom end. The second seal member includes at least one slit in the center of the conically tapered bottom end to allow for passage of instruments.
U.S. Pat. No. 4,978,341 to Niederhauser discloses an introducer valve for a catheter in which an elastomeric valve body is provided with a central longitudinal opening. The valve body has an inner wall tapering inwardly to a central opening, and an outer wall which also tapers inwardly generally parallel with the inner wall. A ring may circumscribe the center of the valve body to bias the central opening into a closed position.
Although attempts have been made to provide a valve assembly which maintains the integrity of the seal between the body cavity and the atmosphere outside the patient's body, seal systems provided to date have failed to address the full range of surgeons' needs, especially when instruments varying in diameter are used.
The present invention provides a valve assembly which may be incorporated into a cannula assembly or utilized in combination with any type of tubular member for introduction into the body of a patient while permitting introduction of instruments through the valve assembly into the body. At all times, the surgeon maintains control over the interface between the atmospheres within and without the patient's body. Moreover, the present invention makes it possible to introduce instruments of varying sizes into the body and insures the maintenance of a gas seal despite instrument manipulation therethrough.